The current, most widely used procedure for diagnostic blood sample collection is venipuncture. This method generally requires a trained phlebotomist and sterile equipment including needles/lancets and collection tubes. The blood samples collected by venipuncture usually require separation by centrifugation and storage under refrigeration. An alternate method uses a lancet for skin piercing such as a finger stick. For example, U.S. Pat. No. 4,920,977 describes a blood collection assembly with lancet and microcollection tube, while U.S. Pat. No. 5,368,047, No. 4,654,513, and No. 5,320,607 each describe suction-type blood samplers. These devices develop suction between the lancing site and the end of the device when the lancet holding mechanism withdraws after piercing the skin. A flexible gasket around the end of the device helps seal the end around the puncture site until adequate sample is drawn from the puncture site or the user pulls back on the device. Finally, U.S. Pat. No. 4,637,403 and Douglas et. al. WO1997042882 disclose combination lancing and blood collection devices which uses a capillary passage to conduct body fluid to a separate test strip in the form of a microporous membrane. With the U.S. Pat. No. 4,637,403 device, it is necessary to achieve a precise positioning of the upper end of the capillary passage with respect to the membrane in order to ensure that body fluid from the passage is transferred to the membrane. If an appreciable gap exists between the two, no transfer may occur—thus careful training and use is needed to properly obtain specimens with this device. The WO1997042882 device solves this problem by affixing a test strip to the capillary tube. Despite these advances in the art of blood collection, they all suffer from the drawback of obtaining liquid samples which must either be tested immediately, or require refrigeration to store and test later, and in any case require extensive use of sterile lab equipment to handle properly.
An alternative method known as dried blood spot (DBS) sampling has also been used for screening newborns for congenital metabolic diseases. In this sampling technique, an infant's heel is pricked by a trained health aide and the blood is spotted on a prepared filter paper. Typically, the spotted filter paper with the blood sample is air dried for several hours before being shipped at ambient temperature to a central state health lab. The blood spot is sampled by a hole punch (3-6 mm diameter), and the punched sample is placed in a tube and eluted with buffer. The extracted sample then undergoes multiple diagnostic tests; a quarter size blood spot sample is sufficient for at least 28 separate tests.
Although DBS has been used for newborn screening, DBS has not been used for routine diagnostic testing. Despite this, numerous studies have shown that DBS sampling is compatible with and equivalent to current diagnostic tests performed with fresh blood samples. Once dried, analytes including DNA, RNA, proteins and small molecules are stable at ambient temperature or under refrigeration for years (De Jesus et al., Clin Chem, 55 (1); 158-164, 2009; McDade, Demography 44(4): 899-925, 2007; Khoo; Pathology International; 61: 1-6, 2011). Analytes are simply extracted from the paper with solvent and measured by traditional methods including LC-MS/MS, RT-PCR, microarray, ELISA, etc. (McDade, Demography 44(4): 899-925, 2007; Haak, Neonatology 95(3), 210-216, 2009). Genetic material can be extracted and isolated from DBS in sufficient quantities for use in genetic analysis. For instance, DBS has been used for the detection of prenatal human immunodeficiency virus (HIV) infection by the polymerase chain reaction (PCR) (Cassol, et al., J. Clin Microbiol. 30 (12): 3039-42, 1992). Dried plasma spot (DPS) and DBS have also been used for HIV RNA detection and quantification (Cassol, et al., J. Clin. Microbiol. 35: 2795-2801, 1997; Fiscus, et al., J. Clin. Microbiol. 36: 258-60, 1998; O'Shea, et al., AIDS 13: 630-1, 1999; Biggar, et al., J. Infec. Dis. 180 1838-43, 1999; Brambilla, et al., J. Clin. Microbiol. 41(5): 1888 93, 2003); HIV DNA detection and quantification (Panteleefe, et al., J. Clin. Microbiol. 37: 350-3, 1999; Nyambi, et al., J. Clin. Microbiol. 32: 2858-60, 1994); and HIV antibody detection (Evengard, et al., AIDS 3: 591-5, 1989; Gwinn, et al., JAMA 265: 1704-08, 1991). HCV RNA detection and genotyping are also reported using DBS (Solmone et al., J. Clin. Microbio. 40 (9): 3512-14, 2002.
However, currently available DBS methods show decreased stability of dried samples when exposed to humidity. Inconsistent application of blood to the filter paper can also result in variable test results. Exposure of the filter paper to air and surfaces during drying or shipment can result in sample contamination. For example, U.S. Pat. No. 6,534,533 provides for a a device to collect and dry blood samples for testing, however, the invention dries the blood using evaporation into the environment, and in various embodiments of the invention, the dried blood spot is exposed to the environment, either directly or through a vapor or fluid permeable membrane. This means that environmental moisture can re-enter the device, potentially damaging or contaminating the sample. Further, separate components, such as a lancet, filter papers, a holder for drying and containers with drying agent for transport are needed for sampling with current DBS methods. These separate components can be cumbersome for use by a skilled technician and are not suitable for use by the patient alone. Furthermore, this method requires disposal of collection materials as hazardous waste.
Consequently, a need exists for improvement in sampling and storage techniques to collect minimal blood amounts in remote locations with minimal training required, no additional infrastructure needs, to ease transport requirements and to improve sample stability.
Additionally, predictable and even distribution of a sample within a sampling material is difficult to obtain with current techniques. Currently, biological sample distribution across the collection material is dependent on sample application technique and can result in uneven analyte concentration across the material. Variable analytical results can occur when a sub-sample within the diameter of the sample spot is removed manually with a hole punch, which is the current and time-consuming method for sample removal. Therefore, there is a need for an apparatus or method that increases the evenness and predictability of sample distribution on collection materials while maintaining or enhancing ease of sample preparation.
The present invention seeks to provide for an all-in-one body fluid collection and storage device as a dried sample providing for increased sample stability/longevity and protection from contamination or degradation.
The present invention further seeks to provide for an all-in-one body fluid collection and storage device containing all of the components necessary to obtain and store the dried sample, increasing ease of use and reducing reliance on outside equipment.
Additionally, the present invention seeks to provide a configuration of collection materials that allows for consistent biological sample distribution and efficient removal of a sub-sample for analysis.